Mining and construction machinery includes wheel loaders, hydraulic excavators, skid steer loaders, multi-terrain loaders, track loaders, and backhoe loaders and the like. Typically implements are mounted to these machines to perform work. One example of such an implement is a bucket. A bucket could be mounted to one of these machines for performing work like digging a trench in the ground, digging material from a pile, or dozing. Another example is a pallet fork. A pallet fork could be mounted for permitting the machine to pickup and carry palletized materials around a building site or at a factory. Still another example is logging forks. Logging forks are specially adapted for picking up and carrying logs. Other non-limiting examples of implements include hammers, blades, brooms, and snow plows.
When a particular implement is attached to the machine, it enables the machine to perform a variety of tasks. In order to perform a task which the implement does not enable the machine to do, a different implement can be attached. The ability to attach multiple implements to a machine so it can perform a variety of tasks—multitasking—increases the utility and value of the machine for the owner.
On the other hand, the attaching and detaching of implements to a machine can be cumbersome and time consuming. The time spent switching implements instead of working reduces the utility of the machine.
Some implements may be mounted to a machine with a simple pin-style joint, which does not facilitate the switching of implements. With this mounting system, a pin is manually inserted into complementary bores in the machine and implement to create a pin joint. Switching implements with this system requires an operator or technician, or multiple technicians, to manually remove the pins that hold the first implement to the machine, remove the first implement, position a second implement on the machine, and manually reinsert the pins. Besides being time consuming, this switching operation can require considerable skill on the part of the operator and technicians.
Quick couplers solve many of the problems that pin-style joints present for switching implements. Quick couplers provide an alternative way to mount implements to mining and construction machinery. The quick coupler is interposed at the junction between machine and implement. The implement is attached to the quick coupler, and the quick coupler is attached to the machine. The operator of the machine commands the quick coupler to release an implement from inside the machine's cab. The machine is then repositioned to a second implement, where the operator may then manipulate the quick coupler and the machine to pickup the second implement. With a quick coupler, changing from one implement to another implement can be done quickly, and typically only requires the involvement of the machine's operator.
Many types and styles of quick couplers for mining and construction machinery have been used and proposed. One example is the coupler disclosed in EP 0 278 571 B1 (hereinafter the '571 coupler).
The '571 coupler suffers from several disadvantages. For instance, the '571 coupler may not create the most favorable wedging action between the coupler and the implement to hold the coupler tightly to the implement, even after possible future wear of the coupling surfaces. The coupling surfaces on the '571 coupler may be prone to sticking problems, making removal of the coupler from the implement difficult. In addition, the '571 coupler may be more expensive to manufacture than it need be.